This invention relates generally to sealing valves for controlling the flow of fluid through a passage defined by the interior surface of a tubular casing, and more particularly to sealing valves for inhibiting particulate material in the fluid from adversely affecting operation of the sealing valve.
Recent improvements in the methods of balancing a pneumatic wheel assembly and reducing the radial and lateral force variations within the wheel assembly under varying load conditions include the introduction of particulate or pulverulent material into a tire. One such method is disclosed in U.S. Pat. No. 5,073,217, which is incorporated herein by reference. The particulate material is mixed with pressurized fluid, such as air, and injected into the wheel assembly through the tire valve stem by a suitable injecting device, such as the device shown and described in U.S. Pat. Nos. 5,386,857 and 5,472,023, which are also incorporated herein by reference. One well-known particulate material is a polymeric synthetic plastic material sold by International Marketing, Inc. under the trademark "EQUAL".
The particulate material is injected into the tire of the wheel assembly with the valve core absent from the valve stem, such as in a new tire prior to installation of the valve core or in an older tire where the valve core has been removed from the valve stem, to allow free flow of the material into the tire. The tire is typically inflated or at least partially inflated during injection of the material into the tire. After injecting the material into the tire, the valve core is installed into the valve stem and the tire is inflated to the desired inflation pressure.
The valve core is a standard sealing valve used for controlling the flow of fluid through a passage defined by the interior surface of a tubular casing, such as the valve stem passage of the valve stem. A valve portion of the valve core opens and closes relative to a stationary valve seat in the passage to control fluid flow through the passage. It is important to the operation of the valve core that the valve and its associated valve seat remain free of particulate material. However, when the valve is opened to release pressurized fluid from the tire or to check the tire pressure, the above described particulate material may be drawn into the valve core and adversely affect operation of the valve core components, as by preventing the valve from fully closing against the valve seat, resulting in fluid continually leaking from the tire. It is also not uncommon for tires to contain other particulate matter such as dust, dirt, or particles of rubber which have dislodged from the interior bead of the tire during use of the wheel assembly. These particles may also be drawn into the valve core and adversely affect operation of the valve core components.
To reduce this risk, it is known to provide a valve stem having a movable filter element permanently enclosed within the valve stem between the valve core and the interior of the tire so that fluid is allowed to flow through the filter element while particulate material is retained within the tire and inhibited from reaching the valve core. For example, the valve stem shown and described in U.S. Pat. No. 5,479,975, which is incorporated herein by reference, includes such a filter. While this valve stem is quite useful, users of particulate material such as EQUAL may desire a method of removably installing a stationary filter into common or standard valve stems already used in the industry rather than replacing the valve stems with those having permanently installed filters.
In our co-pending U.S. patent application Ser. No. 08/762,502, which is incorporated herein by reference, we disclose a tool and method for inserting a filter element into the valve stem of a wheel assembly. The method includes installation of a filter element into the valve stem followed by installation of the valve core into the valve stem whereby the filter element inhibits particulate material in the interior of the tire from flowing to the valve core. However, the valve stem passage and associated valve core and filter element are relatively small, such as less than 0.20 inches in diameter. Because the filter element is separate from the valve core, there is risk of mishandling, dropping and losing the filter element, especially where the persons installing the filter element are wearing gloves, such as in a cold environment.
The use of valve cores or other similar sealing valves to control fluid flow through the passage of a casing is known in other industries as well. For example, valve cores are used to control fluid flow through utility lines, automotive, residential and commercial air conditioning units, carbonated beverage machines, and other apparatus in which it is necessary to control fluid flow through a tubular casing. It is equally important to the operation of valve cores used in these applications that the valve and its associated valve seat remain free of particulate material.